Abstract: A rotor element for a turbocompressor having at least one rotor stage supporting a series of mobile blades that do not have a platform separating the aerofoil from the root of the blade. At least one recess is provided in order to allow the engagement of the roots of the mobile blades, wherein the rotor element comprises at least two consecutive individual rings having at their lateral periphery one annular half-profile which, during the axial juxtaposition of the two individual rings, form a complete recess in which the roots of the series of mobile blades are engaged.